Net income hit $870 million, up 9% from a year earlier. And earnings per share totaled $1.01, beating analysts' forecast of 96 cents, according to FactSet.
But revenue totaled $11.1 billion, trailing expectations of $11.33 billion.
T-Mobile posted 1.7 million total net customer additions in the quarter. It added 1.1 million branded postpaid net accounts included 754,000 branded postpaid phone net additions.
The company reported a record-low third-quarter postpaid phone churn of 0.89%, down 13 basis points from a year earlier.
"Customers show that they want to do business with a company that treats them right and changes the rules of the industry in their favor, and that's what differentiates the Un-carrier from the competition," T-Mobile said in a statement.
T-Mobile shares stood at $82.15 in after-hours trading, down 0.3%, after it finished the regular session up 0.9%.
As for T-Mobile's planned $26.5 billion merger with Sprint, the Justice Department and Federal Communications Commission have approved it. But some states, including New York, oppose the deal, saying it will prompt higher prices for consumers. A multistate lawsuit is scheduled to go to trial in December.
Prior to the earnings report, Morningstar rated the stock as three stars (fairly valued), with exact fair value at $80.50.
"The company continued to win share, taking in 1.7 million net additions, marking its 26th consecutive quarter with more than 1 million net additions," said Chris Versace, CIO and thematic strategist at Tematica Research.
"With AT&T soon to offer HBO Max and Verizon (VZ) - Get Report partnering with Disney's (DIS) - Get Report Disney+, I expect the conversation will soon pivot from just consumer wins and 5G deployment to how T-Mobile will compete on the streaming landscape."
This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.